<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
<script>
var obj1={
    age:18,
    5:'你好',
    sex:'男',
};
obj1.userName='张三';
console.log(obj1.age,obj1['5'],obj1.userName);
console.log('userName' in obj1);
console.log(obj1.hasOwnProperty('sex'));
delete obj1.age;
console.log(obj1.age);

</script>
</body>
</html>